Welcome to this lesson from the unit heredity and DNA.

And the title of today's lesson is "DNA from Fruit." And in today's lesson, we're going to be looking at how we can extract DNA from a kiwi fruit.

This is a practical lesson today.

And we're gonna look at the apparatus and techniques that we're going to use and why those techniques work.

My name's Mrs. Barnard, and I'm going to be taking you through today's lesson.

So by the end of today's lesson, you should be able to observe DNA extracted from fruit and to identify the main apparatus and steps in the extraction method.

There's gonna be some keywords in today's lesson.

So our keywords are as follows.

Cell, DNA, mortar and pestle, filter, and pipette.

Now, the keyword definitions are going to come up now.

You can copy this down, but don't worry, we're gonna go through them later in the lesson.

But if you want to copy them down, just pause the video now.

So our lesson today is in two parts, part one, scientific apparatus and techniques.

And part two, DNA extraction.

So let's get started with the first part of today's lesson, which is scientific apparatus and techniques.

So here's a kiwi fruit.

Hopefully, everyone's had the opportunity to see inside the kiwi fruit before, and it's the fruit of the kiwi plant.

So because it's from a plant, it is made of plant cells.

And you can see underneath the microscope this is a kiwi cell and it's got the features of a cell.

Some of them not that clear in that image, but it does have a cell wall around the outside.

And in the middle, it will have cytoplasm and a nucleus.

It'll have a cell membrane around the outside of its cytoplasm as well.

This is times 400.

So you can see that the cells inside the kiwi fruit are very, very small.

A little bit of a recap for you that a cell is a living building block and they are the living building blocks of all living organisms. So they make up this kiwi fruit.

And all cells contain genetic material that provide the instructions to build an organism to give its features and processes.

And this genetic material is in the form of DNA.

And DNA is made up of smaller chemical units.

And those smaller chemical units allow it to carry a genetic code.

And the genetic code gives the instruction for building features and processes that are required for all living cells.

So this picture is a model of a kiwi cell and you can see it's got some of those features that I just described inside, but we're particularly interested in the nucleus because the nucleus is where the DNA is stored.

So DNA is a chemical substance.

It's a very, very long chemical molecule and we can extract this molecule from the cells.

DNA is usually too small to be seen.

It's just made of chemicals so that we can't see them either with our eyes or down a microscope.

However, if we get lots of it and it's all clumped together, then we will be able to see DNA.

So we've got our kiwi fruit cell here and we've got the nucleus, and then we've got the DNA all wrapped up inside that nucleus.

So time for a quick check.

Which two of these statements about DNA are correct.

Is it's living, it is stored in the nucleus of plant cells, it can usually be seen in the nucleus, or all living organisms have DNA? So if you pause the video, and then we'll come back and see if you've got your answers correct.

So let's have a look at your answers then.

So which two of these statements about DNA are correct? It is living, it is stored in the nucleus of a plant cell.

It can usually be seen in the nucleus or all living organisms have DNA.

So the correct answers were it is stored in the nucleus of plant cells and all living organisms have DNA.

It is not living because DNA is a chemical molecule and it can't be seen in the nucleus.

Because it's a chemical molecule, it's too small to be seen, the DNA itself.

So if you've got those right, then well done.

So extracting the DNA from fruit cells requires the use of scientific apparatus and techniques.

Now, some of these you might have seen before.

So we've got a mortar and a pestle.

And the mortar and the pestle is used to crush and grind up solid samples.

So we're gonna get the fruit, we're gonna take off the skin and the white bit in the middle, and we're gonna crush it up.

And in crushing it up, it releases the cells of the tissue so we can get those individual cells separated.

And then what we're going to do is we're gonna add some salt with a spatula.

Now, salt is imported 'cause it helps to unwind the DNA, but also it's quite a good agent to help grind something up to separate those cells away from each other.

So moving on, we're going to use a pipette.

This is a pasta pipette and the job of the pipette is to move solutions from one place to another.

So in order to use it, you might call them squeezy pipettes.

You need to squeeze the bulb at the end, put it into your solution, and then release.

And then the solution will be taken up into the pipette.

So in this case, we're going to use detergent like a washing up liquid and we're going to put it into the mortar in order to help break up those cell membranes that we talked about being around every cell around the cytoplasm of every cell, just inside the cell wall.

So that helps to break that down.

And then we're gonna use our filtering apparatus.

So in our filtering apparatus, we're going to have a funnel with some filter paper inside.

So you're gonna turn your filter paper into a cone and place that inside and then rest it over the top of a boiling tube or a test tube.

And then we're gonna pour our solution through that.

Now, when we do that, all of the liquid of the solution will move down through the filter paper, through the funnel into the test tube and all the pulp and the seeds will remain in the filter paper at the top.

The next thing that we're gonna do is we're gonna add some alcohol with a pipette.

Now the reason that we're gonna add alcohol is that the DNA will float in the alcohol and it forms clumps and that allows us to be able to see it.

So time for another check.

What I would like you to do is to match the image of the apparatus with the correct name.

So we've got mortar and pestle, filter funnel, test tube, and pipette.

So just pause while you do that and we'll come back and see how you got them.

Okay, so we've got mortar and pestle, that's these here.

So the mortar is like the bowl and the pestle is the post that you crush it up with.

Then we've got the filter funnel, which we put our filter paper into.

And then we've got our test tube.

They're the smaller tubes.

Sometimes boiling tubes might be used which are slightly wider in diameter.

And then we've got the pipette.

And in this case, it's a pasta pipette, squeezy pipette.

Okay, so let's move on to our practise task.

Now, in this practise task, what I would like you to do is to complete the sentences to explain why each of these scientific techniques were used.

So all of these reasons were given in the previous slides.

So we need to write out these five sentences with the reason why that technique was used.

So pause video while you do it, and then we'll see how you've got on.

Okay, let's see how you've done with that then.

So first one, crush the fruit cells with a mortar and a pestle to release the cells from the tissue.

Add a detergent to the solution with a pipette, and that's to break open the cell membranes.

And we've got add salt to the solution with a spatula, and that's to unwind the DNA.

And then we've got filter the solution with filter paper and that's to remove the pulp and seeds.

And finally, we've got add alcohol using a pipette and we do that to make the DNA float and form clumps.

So if you've got all of those reasons for the techniques correct, then well done.

Now, we're moving on to the second part of our lesson, which is DNA extraction.

So we've got a video here for you to watch to see the process for extracting your DNA from kiwi fruit and explains the steps in the method so that if you're going to take part in this experiment today, then you'll know exactly what to do.

This is a video about how to extract DNA from kiwi fruit or other fruits like strawberries.

First of all, you have to remove the skin and the white part in the middle to just get to the flesh 'cause we want to be able to get the cells out of the flesh.

Then we're gonna chop it up and we're gonna put it into the mortar and we're gonna crush it with the pestle.

Then gonna add some salt.

And the salt's useful because it helps us to crush it to release those cells from the kiwi tissue, but also because it helps to unravel the DNA.

Then we're gonna use a pipette and we're gonna now add some detergent.

So this is like a washing up liquid.

And we're gonna add it to the mortar and then we're gonna continue to crush it with the pestle, mixing it up until we've got a mixture.

Then we're gonna set up our filtering apparatus.

We've got some filter paper there inside a funnel.

We're going to pour our mixture into the filter paper, and then we're going to let it rest.

Now the solution is gonna come through the filter paper and it's gonna come down into the test tube.

Now, we add our ice cold ethanol.

Now, when you add your ethanol, you've got to add it very slowly drip by drip down the side of the test tube.

Now, the reason that we add ethanol is because it is less dense than the solution, so it floats on the top, and it causes the DNA to float in a band.

So when we look at this really closely, we can see that the DNA is in the band of ethanol that's on the top.

It's that furry white substance there inside the ethanol.

And that's our kiwi fruit DNA.

So hopefully, you were able to follow that.

But let's go through the method here.

You also should have this available as an additional material sheet that you could maybe read alongside doing the practical if you've got the opportunity to do that today.

So the method is to take a quarter of a kiwi fruit and to remove the skin and the white centre with a scalpel on a tile.

Make sure that you're cutting downwards with the scalpel to keep yourselves safe.

And we're only carrying scalpels around in a tray and we're making sure that they're not pointing outwards.

Next, chop.

Next, chop it into pieces, and then place it into the mortar.

Remember the mortar is the bowl-shaped apparatus.

And then we're going to crush it and mix it up with salt for two minutes.

Then we're gonna use a pipette and we're gonna add two centimetres cubed of detergent.

It will have little numbers on the side of your pipette.

So you want number two of those.

And then we're gonna crush and mix these together for two minutes.

Then you're gonna make your filter paper into a cone.

So fold it into quarters and then put your fingers between the leaves that you've made and you should be able to make a cone and place it in the filter funnel over a test tube or a boiling tube.

Then you're gonna pour the mixture that's in the mortar into the filter paper and you're going to wait for the solution to filter through.

Now, this might take a little bit of time because the seeds and the pulp sometimes block up the little holes in the filter paper.

You can give it a gentle stir inside there just to encourage it to move through.

And then you're gonna remove the filter funnel from the test tube, and then add two centimetres cubed of ice cold ethanol with a pipette, trickling it down the side of the test tube nice and slowly because you want that band of alcohol to float on the surface.

Okay, so from what I've just said there, I would like you to put the statements in order to describe how you would extract DNA from a kiwi fruit.

So pause the video while you do this and we'll come back and make sure that you've got these in the correct order.

Let's see how you got on then.

So the first stage is to cut off the skin and the centre from the kiwi.

And then number two is to crush the kiwi with salt and detergent in the mortar.

The third stage is to filter the kiwi mixture with filter paper and a funnel.

And then the final stage is to add alcohol to the kiwi solution.

Remember, we're adding that slowly drip by drip down the side.

So if you've got the order of those correct, well done.

So it should be C, A, D, B.

So your activity task, your practise task for this is to either carry out the practical yourself, okay, with your teacher supervision, or to watch a demonstration of the DNA being extracted from the kiwi fruit.

And what I would like you to do is to use your observation skills to draw a label diagram of the results.

And then I would like you to explain why you are able to see the DNA with your eyes.

So it'll take you a little bit of time to do this and make sure that your drawings are nice and neat with a pencil and a ruler.

So pause the video and then come back and we'll see how you've got on.

All right then, let's have a look at what you've included in your diagrams. So you should have observed a result that looks similar to this.

So you should have had a layer of alcohol with clumps of DNA floating in that layer of alcohol.

And then a layer of filtered fruit extract that's at the bottom.

So that's the parts of the filtered kiwi that isn't DNA will fall to the bottom of the test tube.

So if you were to draw a diagram of that, we'd expect a pencil diagram where you can see those layers and you've labelled it in the same way.

And the explanation should match the one underneath, which is that the DNA is the white fluffy substance or the substance floating in clumps in the alcohol layer in the test tube.

And the DNA is visible because it's been extracted from the fruit cells and there's a lot of it and it's clumped together.

So if you've got all that correct, well done, that's great.

Hopefully, you got the opportunity to see this live, but if not, then you know the procedure to follow.

So we come to the summary of today's lesson.

So DNA is a chemical substance that can be extracted from the cells of organisms such as fruit.

DNA molecules cannot usually be seen with the unaided eye.

This is because they're too small and they are stored within the nucleus.

When a lot of DNA is extracted, it can be seen in clumps.

The main apparatus required to extract DNA is mortar and pestle, funnel and filter paper, test tube and pipette.

The main techniques used in extracting DNA are crushing with a mortar and pestle, filtering with filter paper and a funnel, and transferring liquids with a pipette.

Well done for your work in today's lesson.